P&C re-ring question
 

I'm planning on reusing my Nickasil cylinders and not re-ring (100k on them). Can I separate pistons from the cylinders?

Say I want to inspect the rings. Or if I accidentally pull them apart when disassembling. Do the rings need to re-seat if they're rotated differently? Would it be advisable to have them deglazed or machined in any way?

I've done 2 top end overhauls on Nicasil engines and re-used the rings. I took them apart to check the wear and clean the ring lands. I put them back in the same position on the piston with the top ring oriented the same way it came out. The other rings I oriented to keep the gaps 120 degrees away from each other. Never had a problem. The engine runs as if the rings were never removed. I think the rings probably creep around in the cylinders anyway.

So you'll pull them apart, clean 'em, orient the rings the way you want them (which may not be exactly how they were when you pulled them out) and re-assemble. No de-glazing, no nothing?

Sounds pretty straightforward. They re-seat without any problems?

c

That is correct. The first engine I did I tried to orient them the way they were before. (probably plus or minus 20 degrees) The second one I just oriented the top ring to where it was when it came out. I don't believe that you need to do that but I didn't want to take a chance. Both engines ran like the rings were still seated after the rebuild. I did put all the rings back on the same cylinder and piston groove that they came from. Be sure to notice that the rings have a top and bottom. I used shims to keep the ends of the rings from scratching the pistons.

You need to measure the wear buy checking the ring clearance in the piston groove and the end gap in the cylinder. The haynes manual and 911 performance hadbook show you how to do this.

Why seperate if you don't have to. Keep them together unless you suspect a problem. Simplify the potential for problems.

to get the G.. D.... broken head studs out i woudl guess...

PLus, I would want to measure the wear on the rings to make sure I could reuse them.

You don't have to pull the heads apart to get the studs fixed. Pull the heads and cams as a unit, pull the P&C's as a unit, fix the head studs, install the P&C's, Install the heads, done.

I'm in the middle of doing it myself. Different reason, but same net effect.

The engine is getting pulled apart for a top-end job. Needless to say, the heads will be coming apart and heading off to the machinist. The P&C's I intend to pull together, but since I've got about 100k on the clock, I'm interested in measuring the ring gap. I'll also try to clean the piston tops and may have a small amount machined off the cylinder bases for a small compression bump. This all depends on how much deck height I have when disassembling. If I go down this path, I'll have to separate Ps & Cs.

Michael, how's your engine going?

Chris

Sending the block to the machine shop this week to have is cleaned. I got all the Loctite off it. That was a lot of work and 99.9% sure as to the cause of why it leaked. it was really thick around the #8 bearing which tells me it was setting up before I could get it sealed down. I'm going to have the machine shop check the block for tolerances as well while it's there to make sure it's all good. Saturday is the day to put it back together again.

Michael,

Who is your local machine shop? I'm using Colorado Automotive Machine for my heads.

c